Transmission device

ABSTRACT

A transmission is provided including a splitter shaft having a concentric cavity defined in a distal end thereof and an outer wall surrounding the cavity. The outer wall has an increased thickness in order to reduce failure and fracturing in the outer wall area. A bearing hub adapted for supporting a larger bearing is also provided. The improved transmission may include a system for utilizing existing lubrication lines in order to lubricate a center section of the transmission. The components of the present invention may be provided as part of a kit for retrofitting an existing transmission in order to reduce failures and increase lifespan.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of U.S. applicationSer. No. 13/936,970 filed Jul. 8, 2013.

TECHNICAL FIELD

The present disclosure relates generally to transmissions. Moreparticularly, the present disclosure relates to an improved centersection of a transmission which includes components such as a mainbearing and splitter shaft. Further, the present invention also relatesto an improved system and method for lubricating components in thecenter section of a transmission.

BACKGROUND OF THE INVENTION

Transmissions are well known in the prior art. Transmissions havediverse applications and can be used in areas which include, forexample, automobiles, oil-field pumping and fracturing units,off-highway trucks, agricultural tractors, and winch units, such asthose on derricks and cranes. As depicted in FIG. 1, a transmission 10may be used to couple an engine 12 to a pump 14 on a fracking pump unit16. When used in this capacity, the transmission undergoes significantstress as the pump produces significant power requirements (e.g.,2,000-2,500 HP) and torque loads. Due to such conditions, thetransmission 10 may only last around 500 hours in this type ofapplication.

It is known in the prior art that certain components within thetransmissions are generally subject to short life failures. For example,components such as the main bearing and splitter shaft generally tend toexperience premature failure. It is an object of the present inventionto increase the life expectancy of these components by creating newcomponents and remanufacturing existing components to increase theirlife expectancy over the prior art.

Further, it is also known that transmissions in the prior art useinefficient systems and methods for lubricating the main bearing in thecenter section of the transmission housing. It is an object of thepresent invention to directly lubricate the bearings in the center ofthe transmission through use of a lubrication tube that can spraylubrication directly onto those bearings.

BRIEF SUMMARY OF THE INVENTION

The present invention involves the provision of an improved transmissionhaving an increased lifespan and lower failure rate as compared toprevious transmissions. A system and method are provided forretrofitting existing transmissions.

One embodiment of the transmission of the present invention includes acenter section comprising an improved splitter shaft, main shaft andbearing located radially therebetween. In one embodiment, the splittershaft has a concentric cavity defined in a distal end thereof and anouter wall surrounding the cavity. In order to reduce failure, the outerwall has an increased radial thickness, for example, a radial thicknessof between about 0.50 inches and 0.75 inches in one embodiment and about0.65 inches in another embodiment. In one embodiment, the distal end ofthe splitter shaft has an outer diameter of about 2.6 inches and itscavity has an outer diameter of about 1.3 inches. As such, the ratio ofthe diameter of the distal end of the splitter shaft to the diameter ofits cavity is between about 1.5 and 2.5 in one embodiment and is about2.0 in another embodiment.

The main shaft includes a concentric pilot member extending axially froma distal end thereof and extending into the cavity of the splittershaft. A bearing can be located radially between the pilot member of themain shaft and an inner wall of the cavity of the splitter shaft. Thepilot member can have an outer diameter of about 0.99 inches. In oneembodiment, the ratio of the outer diameter of the pilot member to thediameter of the cavity is between about 0.70 and 0.85 in one embodimentand about 0.78 in another embodiment.

The improved transmission may also include a bearing hub having anaxially-extending circular flange adapted for supporting an outer raceof a bearing, wherein the flange has an inner diameter of between about5.0 inches and 6.0 inches in one embodiment and about 5.5 inches inanother embodiment. The bearing hub of the present invention is adaptedfor receiving larger bearings than presently used in prior art designs.

The improved transmission may further include a new tube attached to anexisting, non-used lubrication line via a threaded connection and aspray orifice located at a distal end thereof. A method for lubricatinga center section of the transmission may comprise the steps of locatingan existing lubrication line that runs adjacent the center section ofthe transmission, inserting a threaded connection into the lubricationline, attaching a new tube onto the threaded connection, running the newtube to a location adjacent components within the center section; andattaching a spray orifice to a terminal end of the tube.

Other and further objects of the invention, together with the featuresof novelty appurtenant thereto, will appear in the course of thefollowing description.

DESCRIPTION OF THE DRAWINGS

In the accompanying drawings, which form a part of the specification andare to be read in conjunction therewith in which like reference numeralsare used to indicate like or similar parts in the various views:

FIG. 1 is a side perspective view of a trailer including an engine,transmission and pump mounted thereon in accordance with the prior art;

FIG. 2 is a schematic cross-sectional side view of a transmission inaccordance with the prior art;

FIG. 3A is an enlarged cross-sectional view of a center section of atransmission in accordance with the prior art;

FIG. 3B is an enlarged cross-sectional view of a center section of atransmission in accordance with one embodiment of the present invention;

FIG. 4A is a perspective end view of a splitter shaft of a transmissionin accordance with the prior art;

FIG. 4B is a perspective end view of a splitter shaft of a transmissionin accordance with one embodiment of the present invention;

FIG. 5A is a side view of a main bearing of a transmission in accordancewith the prior art;

FIG. 5B is a side view of a main bearing of a transmission in accordancewith one embodiment of the present invention;

FIG. 6A is a side view of a main bearing hub of a transmission inaccordance with the prior art;

FIG. 6B is a side view of a main bearing hub of a transmission inaccordance with one embodiment of the present invention; and

FIG. 7 is a side perspective view of a lubrication line in accordancewith one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The invention will now be described with reference to the drawingfigures, in which like reference numerals refer to like partsthroughout. For purposes of clarity in illustrating the characteristicsof the present invention, proportional relationships of the elementshave not necessarily been maintained in the drawing figures.

The following detailed description of the invention references specificembodiments in which the invention can be practiced. The embodiments areintended to describe aspects of the invention in sufficient detail toenable those skilled in the art to practice the invention. Otherembodiments can be utilized and changes can be made without departingfrom the scope of the present invention. The present invention isdefined by the appended claims and the description is, therefore, not tobe taken in a limiting sense and shall not limit the scope ofequivalents to which such claims are entitled.

One embodiment of the present invention is generally directed to a kitfor retrofitting and improving the lifespan of a prior art transmission,such as for example, an Allison 59820 transmission.

FIG. 2 illustrates a cross-sectional view of a prior art transmission 10that includes an input shaft 18, which is typically coupled to an engine12, and an output shaft 20, which is typically coupled with a pump 14.Between the input shaft 18 and output shaft 20 is a center section ofthe transmission 10 comprising a main shaft 22 and a splitter shaft 24.The center section shown is a planetary section. As shown in greaterdetail in FIG. 3A, a rear or distal end 26 of the main shaft 22 isrotationally supported by a front or distal end 28 of the splitter shaft24. As illustrated, the rear end 26 of the main shaft 22 includes aconcentric pilot member 30 extending axially therefrom. The end 28 ofthe splitter shaft 24 includes a concentric opening or cavity 32 definedtherein. A pilot bearing 34, inserted into cavity 32, is provided forrotationally supporting the pilot member 30 within the cavity 32.

In one prior art transmission, for example an Allison 59820transmission, the outer diameter D₁ of the end 28 of the splitter shaft24 is approximately 2.57 inches, as shown in FIG. 4A. The diameter D₂ ofthe cavity 32 of the same splitter shaft 24 is approximately 2.04inches, resulting in an outer wall 36 having a thickness T₁ of only 0.26inches. This thin wall 36 of the splitter shaft 24 is a common point offailure in the prior art design shown in FIGS. 3A and 4A. Over time, thethickness T₁ of this outer wall 36 was not sufficient to withstandforces acting on the wall 36 and thus would eventually lead to fractureof the splitter shaft 24 in this area. This is especially true when thetransmission 10 was used to drive a pump 14 in a fracking operation.Therefore, a need existed for a splitter shaft that would avoid fractureat the outer wall 36 area of the shaft.

An improved main shaft 38 and splitter shaft 40 are shown in FIG. 3B. Asillustrated in FIGS. 4A and 4B, the outer diameter D₃ of the splittershaft 40 may remain the same as the outer diameter D₁ of the prior artsplitter shaft 24 so that the new splitter shaft 40 may be retrofittedinto an existing transmission, such as an Allison 59820 transmission.However, the diameter D₄ of the concentric cavity 42 of the new splittershaft 40 is substantially smaller, thereby resulting in a thicker outerwall 44. In one embodiment, the outer diameter D₃ is approximatelybetween about 2.25 inches and 2.75 inches (e.g., 2.57 inches) and thediameter D₄ of the cavity 42 is approximately between about 1.0 inch and1.5 inches (e.g., 1.27 inches), resulting in an outer wall 44 having athickness T₂ of between about 0.50 inches and 0.75 inches (e.g., 0.65inches). In other words, the thickness T₂ of the outer wall 44 (e.g.,0.65 inches) in the improved design is between about two and three timesgreater than the thickness T₁ of the outer wall 36 (e.g., 0.26 inches)in the prior art design. It will be appreciated that this increasedthickness results in the improved splitter shaft 40 having fewerfailures and a substantially longer life as compared to the previoussplitter shaft 24. The ratio of the outer diameter D₃ of the distal end92 of the splitter shaft 40 to the diameter D₄ of its cavity 42 isbetween about 1.5 and 2.5 in one embodiment and is about 2.0 in anotherembodiment. It will be further appreciated that the dimensions of thesplitter shaft 40 provided herein are simply examples and other suitabledimensions may be employed in various embodiments.

As illustrated in FIG. 3B, because the diameter D₄ of the cavity 42 ofthe improved splitter shaft 40 is smaller than the diameter D₂ of thecavity 32 of the prior art splitter shaft 24, the area and volume forreceiving the pilot member 46 and pilot bearing 48 are smaller. In theprior art, the pilot bearing 34 is a ball bearing, whereas in theimproved design, the pilot bearing 48 can be a needle bearing, brassbushing or other similar low profile bearing or bushing in order tocompensate for the smaller diameter D₄ of cavity 42. In such anembodiment, it will be appreciated that the prior art main shaft 22 neednot be exchanged. Instead, the original pilot ball bearing 34 may simplybe replaced with a new pilot bushing or bearing 48 having a smallerouter diameter as compared to the diameter of the original pilot ballbearing 34. However, in some embodiments, the original main shaft 22 mayoptionally be replaced with a new main shaft 38 having a concentricpilot member 46 with a smaller outer diameter as compared to thediameter of the pilot member 30 of the original main shaft 22. The outerdiameter of the pilot member 46 may be between about 0.75 inches and1.25 inch and, in one embodiment is about 0.99 inches. As such, theratio of the outer diameter of the pilot member 46 to the diameter D₄ ofthe cavity 42 can be between about 0.5 and 1.0 in one embodiment,between about 0.70 and 0.85 in another embodiment and about 0.78 in afurther embodiment.

The main shaft 38 and splitter shaft 40 can be formed of any suitablemetallic material and, in one embodiment, can be formed of AISI 1043steel or AISI 4320 steel. As illustrated in FIG. 3B, like with the priorart, the main shaft 38 and splitter shaft 40 are splined and includelongitudinally-extending splines or teeth 50 and 52, respectively,protruding radially from the exterior surfaces thereof.

Another cause of failure within prior art transmissions was due to themain bearing 54, which is located generally around the splitter shaft24. FIG. 3A depicts a prior art main bearing 54 located around thecircular hub 78 of a splitter ring gear 76 positioned at the front end28 of the splitter shaft 24. The hub 78 of the splitter ring gear 76includes internal splines or teeth which mate with the external splinesor teeth of the splitter shaft 24. As shown in FIG. 5A, the prior artmain bearing 54 includes an inner race 56, an outer race 58 and rollerballs 60 located there between, as is well known. The inner race 56 hasan inner diameter D₅ enabling the bearing 54 to be placed around the hub78 of a splitter ring gear 76, as illustrated in FIG. 3A. Further, theouter race 58 has an outer diameter D₆ enabling the bearing 54 to beplaced within a circular flange 64 of a static bearing hub 62 having aninner diameter D₉, which can be about 5.51 in one embodiment. In oneprior art transmission, for example an Allison S9820 transmission, theinner diameter D₅ of the inner race 56 is about 3.74 inches and theouter diameter D₆ of the outer race 58 is about 5.11 inches.

An improved main bearing hub 66 is provided in the present invention inorder to accommodate a larger main bearing 70. The new bearing hub 66has a flange 68 with a larger inner diameter D₁₀ in order to accommodatea main bearing 70 having an outer race 74 with a larger outer diameterD₈ as compared to the outer diameter D₆ of the previous main bearing 54.

In one embodiment, the inner diameter D₁₀ of flange 68 is about 5.5inches. The flange 64 of a prior art bearing hub 62 can be machined todecrease the thickness of the flange 64 in order to accommodate a largermain bearing 70. In this way, a new bearing hub 66 can be remanufacturedfrom an existing prior art bearing hub 62. In another embodiment, a newhub assembly 66 can be created anew in order to meet the largerdimensional requirements of the larger bearing 70 of the presentinvention. In this case the flange 68 of hub 66 could have a largerouter diameter D11 than the outer diameter D12 of flange 64 of hub 62.To accommodate the increase in outer diameter D11, the diameter of anexisting orifice 100 in a dividing wall 102 of the existing transmissionhousing 103 would have to be increased to accommodate the increaseddiameter D11. This could be accomplished by machining the inner sidewall101 delimiting the orifice 100.

The inner race 72 of the new bearing 70 can have an inner diameter D₇that is equal to the inner diameter D₅ of the inner race 56 of theprevious main bearing 54. Alternatively, the inner race 72 of the newbearing 70 can have an inner diameter D₇ that is suitable for placementaround a hub 78 that is larger or smaller than the hub 78 of theprevious splitter ring gear 76. In one improved embodiment, the innerdiameter D₇ of the inner race 72 is about 3.93 inches and the outerdiameter D₈ of the outer race 74 is about 5.51 inches. The splitter ringgear 76 may be replaced or modified in order to include a hub 78 that isappropriately sized relative to the inner diameter D₇ of the inner race72 of the new main bearing 70. For instance a sleeve can be fittedaround the hub 78. It will be appreciated that the dimensions of the newbearing 70 provided herein are simply examples and other suitabledimensions may be employed in various embodiments. Both the radialthickness and the axial thickness of the new main bearing 70 may beincreased relative to the original bearing 54. It will further beappreciated that the new main bearing 70 may be press fit onto the hub78 of the splitter ring gear 76 and press fit into the flange 64 of thebearing hub 62.

The prior art transmission 10 also includes a lubrication line 84 whichwas originally used to provide lubrication for a speedometer gear withinthe transmission housing of the prior art transmission. The lubricationline 84 carried lubrication, such as oil, from an oil cooler to thespeedometer gear. However, the speedometer gear is typically no longerused in most transmissions and the lubrication line 84 remains unused.As illustrated in FIG. 3A, the lubrication line 84 runs past the centersection of the transmission 10.

In one embodiment of the present invention, the lubrication line 84 isrepurposed for directing lubrication to the components in the centersection of the transmission such as the main bearing hub 66, mainbearing 70, splitter ring gear 76 and splitter shaft 40, for example. Inorder to repurpose the existing lubrication tube 84, a person ofordinary skill in the art only needs to add a threaded connection or tap86 onto the existing tube 84. From this threaded connection 86, the usercan then connect a new tube 88 and run this new tube 88 to a desiredlocation adjacent the center section, as demonstrated in FIGS. 3B and 7.The new tube 88 can include a terminal end having one or more sprayorifices 90 to deliver the lubrication to the directed components. Ashutoff valve (not shown) can optionally be added downstream of thenewly added threaded connection 86 to divert all the lubrication to thecenter section components.

A method for lubricating a center section of the transmission 10 maycomprise the steps of locating an existing lubrication line 84 that runsadjacent the center section of the transmission 10, inserting a threadedconnection 86 into the lubrication line 84, attaching a new tube 88 ontothe threaded connection 86, running the new tube 88 to a locationadjacent components within the center section, and attaching a sprayorifice 90 to a terminal end of the tube 88.

From the foregoing, it will be seen that this invention is one welladapted to attain all the ends and objects hereinabove set forthtogether with other advantages which are obvious and which are inherentto the structure. It will be understood that certain features and subcombinations are of utility and may be employed without reference toother features and sub combinations. This is contemplated by and iswithin the scope of the claims. Since many possible embodiments of theinvention may be made without departing from the scope thereof, it isalso to be understood that all matters herein set forth or shown in theaccompanying drawings are to be interpreted as illustrative and notlimiting.

The constructions described above and illustrated in the drawings arepresented by way of example only and are not intended to limit theconcepts and principles of the present invention. Thus, there has beenshown and described several embodiments of a novel invention. As isevident from the foregoing description, certain aspects of the presentinvention are not limited by the particular details of the examplesillustrated herein, and it is therefore contemplated that othermodifications and applications, or equivalents thereof, will occur tothose skilled in the art. The terms “having” and “including” and similarterms as used in the foregoing specification are used in the sense of“optional” or “may include” and not as “required”. Many changes,modifications, variations and other uses and applications of the presentconstruction will, however, become apparent to those skilled in the artafter considering the specification and the accompanying drawings. Allsuch changes, modifications, variations and other uses and applicationswhich do not depart from the spirit and scope of the invention aredeemed to be covered by the invention which is limited only by theclaims which follow.

What is claimed is:
 1. A transmission comprising: a splitter shafthaving a concentric cavity defined in a distal end thereof and an outerwall extending around said cavity, said outer wall having a radialthickness of about 0.65 inches; a main shaft having a concentric pilotmember extending axially from a distal end thereof and extending intosaid cavity of said splitter shaft; and a bearing located radiallybetween said pilot member and an inner surface of said outer wall, saidinner surface delimiting a diameter of said cavity in a radialdirection.
 2. The transmission of claim 1, wherein said distal end ofsaid splitter shaft has an outer diameter and wherein a ratio of saidsplitter shaft outer diameter to said cavity diameter is between about1.5 and 2.5.
 3. The transmission of claim 1, wherein said distal end ofsaid splitter shaft has an outer diameter and wherein a ratio of saidsplitter shaft outer diameter to said cavity diameter is about 2.0. 4.The transmission of claim 1, wherein said distal end of said splittershaft has an outer diameter of about 2.6 inches and said cavity diameteris about 1.3 inches.
 5. The transmission of claim 1, wherein said pilotmember has an outer diameter and wherein a ratio of said pilot memberouter diameter to said cavity diameter is between about 0.70 and 0.85.6. The transmission of claim 1, wherein said pilot member has an outerdiameter of about 0.99 inches and said cavity has an outer diameter ofabout 1.26 inches.
 7. The transmission of claim 1, wherein said splittershaft is a replacement shaft that replaces an existing splitter shaft ofsaid transmission having an outer wall with a radial thickness of about0.26 inches.
 8. The improved transmission of claim 1 further comprisinga bearing hub having an axially-extending circular flange adapted forsupporting an outer race of a bearing, said flange having an innerdiameter of between about 5.0 inches and 6.0 inches.
 9. The transmissionof claim 8, wherein said flange has an inner diameter of about 5.5inches.
 10. The improved transmission of claim 8, wherein said bearinghub is a replacement hub that replaces an existing bearing hub of saidtransmission having a flange with an inner diameter of about 5.1 inches.11. The transmission of claim 1 further comprising a threaded connectionattached to an existing lubrication line, a tube attached to saidthreaded connection and a spray orifice attached to a terminal end ofsaid tube.